Dynamic force measurement system for tire testing station

Abstract

The invention provides a system and method for measuring tire forces wherein the force contributions of the test machine may be separated from the force contributions of the tire. The invention achieves the separation of the forces by equipping the test station with a plurality of accelerometers that allow the forces and the moments of the components of the measurement station to be calculated and accounted for in the overall force measurement. In one embodiment, the test station uses a slip ring disposed between the rotating rotor to which the tire is mounted and the stationary bearing housing to allow data to be easily gathered from the accelerometers mounted on the rotor. The slip ring also allows tires to be easily mounted and dismounted.

What is claimed is:  
     
       1. A test station apparatus for measuring tire force, the apparatus comprising: 
       a base;  
       a recording device;  
       a force measurement device connected to the base; the force measurement device adapted to measure a first set of tire forces;  
       a bearing housing connected to the force measurement device;  
       a rotor rotatably mounted to the bearing housing, the rotor adapted to hold a wheel and tire assembly;  
       at least one accelerometer mounted to the rotor, the accelerometer being in communication with the recording device;  
       a slip ring connected to the rotor and the bearing housing;  
       the slip ring providing a portion of the communication between the accelerometer and the recording device; and  
       means for calculating at least one rotor force from data obtained from the at least one accelerometer mounted to the rotor; and  
       means for adding the at least one rotor force to the first set of tire forces.  
     
     
       2. The apparatus of  claim 1 , wherein four accelerometers are mounted to the rotor. 
     
     
       3. The apparatus of  claim 2 , wherein the four accelerometers are spaced apart by 90 degrees. 
     
     
       4. The apparatus of  claim 1 , further comprising at least one accelerometer mounted to the bearing housing. 
     
     
       5. The apparatus of  claim 4 , wherein four accelerometers are mounted to the bearing housing. 
     
     
       6. The apparatus of  claim 5 , wherein the four accelerometers are spaced apart by 90 degrees. 
     
     
       7. The apparatus of  claim 1 , further comprising at least one accelerometer mounted to the force measurement device. 
     
     
       8. The apparatus of  claim 7 , wherein four accelerometers are mounted to the force measurement device. 
     
     
       9. The apparatus of  claim 8 , wherein the four accelerometers are spaced apart by 90 degrees. 
     
     
       10. The apparatus of  claim 1 , further comprising means for rotating the rotor. 
     
     
       11. The apparatus of  claim 10 , further comprising means for reading the accelerations measured by the accelerometer and calculating the rotor forces. 
     
     
       12. The apparatus of  claim 1 , wherein the slip ring has a first portion that moves with the rotor and a second portion that is connected to the bearing housing. 
     
     
       13. The apparatus of  claim 12 , wherein the slip ring is surrounded by the combination of the rotor and the bearing housing. 
     
     
       14. A method of measuring tire forces at a test station apparatus; the method comprising the steps of: 
       mounting a tire to a test station having a base, a force measurement device, a bearing housing, and a rotor;  
       rotating the tire and measuring the tire forces with the force measurement device;  
       calculating the force of at least the rotor; and  
       adding the force calculated for the rotor to the tire force measured by the force measurement device.  
     
     
       15. The method of  claim 14 , further comprising the steps of calculating the force of at least the bearing housing and adding the force calculated for the bearing housing to the tire force measured by the force measurement device. 
     
     
       16. The method of  claim 15 , further comprising the steps of calculating the force of at least the force measurement device and adding the force calculated for the force measurement device to the tire force measured by the force measurement device. 
     
     
       17. The method of  claim 14 , further comprising the step of providing the rotor with four accelerometers. 
     
     
       18. The method of  claim 17 , further comprising the step of providing the bearing housing with four accelerometers. 
     
     
       19. The method of  claim 18 , further comprising the step of providing the force measurement device with four accelerometers. 
     
     
       20. The method of  claim 14 , wherein the step of adding the force calculated for the rotor to the tire force measured by the force measurement device substantially eliminates the force measured for the rotor from the total measured force to yield substantially only the force of the tire.